The invention relates to an auxiliary tool for levelling a finishing floor made of flowable mortar or similar material, whereby at each desired location of a floor or a building an exact floor height or level for the finishing layer to be provided is plotted by means of a separate mortar plug, said tool comprising a laser receiver.
In addition to the finishing floor being horizontally level or extending with a perdetermined slant, the finishing floor should be smooth when receiving a floorcovering or when being the "surface layer".
Up until now, a board or stick has been used as an auxiliary tool. The board has at its upper end a laser receiver, or simply receives a laser beam or visibly thereon when the laser beam passes thereon. The board has at its lower end a horizontal transverse member, for example, a tile. In use, the bottom surface of the tile is placed in the same plane as a level mark provided on a wall of the building in which the finishing floor has to be provided (the mark being, for example, a couple of centimeters below the lower threshold of a door opening). To place the tile in the proper plane, the tile is made to rest on a mortar plug, built up to the proper height. Thereafter, the laser receiver is adjusted at each desired floor location to the height of the laser beam, and an amount of mortar is placed on the floor, the tile being pressed on top of the mortar until the laser beam coincides with the receiver, whereby the upper surface of the mortar comprises the exact floor height or level. After the partial hardening of the floor the mortar plugs are removed, and the holes formed thereby are filled with the same material as the finishing floor.
It is also possible when using flowable mortar to hold the board at the coinciding height of the laser beam until the layer, flowed onto the underfloor, reaches the lower surface of the board or tile (see U.S. Pat. No. 4,114,220). However, this second method is very inaccurate.
The use of the board as an auxiliary tool has a disadvantage of requiring a laborious process as follows:
first the location in which a mortar plug is to be provided is moistened by a brush and water;
secondly, the location is made adhesive by mortar slurry (mortar having a large cement concentration); and
thirdly, the mortar is placed by means of a trowel;. and thereafter the tile is placed onto the mortar and the height adjusted.
Due to the laboriousness of the process one often determines the floor height with few mortar plugs distances from each other, which is not very accurate. Also, moistening and making the floor adhesive is often eliminated. Thus, if the floor is not very rough, the mortar does not adhere thereto and remains loosely positioned, so that when thereafter the finishing floor is poured, the mortar plugs may shift, and again, inaccuracies occur.
From DE-A-No. 2827521 a tool is known for levelling floors, comprising an outer tube erected vertically to the floor by means of three supporting legs connected thereto. A second tube, vertically slideable within the outer tube carries graduated indicia. A horizontal plate is attached at the lower end of the entire tube. The desired level of the plate above the underfloor is adjusted through a sighting instrument or a laser beam. The flowable mortar has to be swept over the floor until it reaches the lower plate surface. It is a disadvantage of this method that it is not very accurate.
Furthermore, a frame is known from EP-A-No. 0077070 which is provided with a laser detector. A vertical tube is carried by the frame, which may be lowered onto an amount of adhesive present on the underfloor. As determined by coincidence of the laser beam, a lower portion of the tube is cut therefrom through the use of a circular saw provided on the frame. These plugs that are so cut and left on the floor have the desired height for the finishing floor. The apparatus has the disadvantage that it is large, and it requires an electric current supply for the circular saw.
The invention aims at removing the foregoing disadvantages.